arch/powerpc/kexec/crash.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Architecture specific (PPC64) functions for kexec based crash dumps.
  *
  * Copyright (C) 2005, IBM Corp.
  *
  * Created by: Haren Myneni
  */

 #include <linux/kernel.h>
 #include <linux/smp.h>
 #include <linux/reboot.h>
 #include <linux/kexec.h>
 #include <linux/export.h>
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
 #include <linux/types.h>

 #include <asm/processor.h>
 #include <asm/machdep.h>
 #include <asm/kexec.h>
 #include <asm/prom.h>
 #include <asm/smp.h>
 #include <asm/setjmp.h>
 #include <asm/debug.h>

 /*
  * The primary CPU waits a while for all secondary CPUs to enter. This is to
  * avoid sending an IPI if the secondary CPUs are entering
  * crash_kexec_secondary on their own (eg via a system reset).
  *
  * The secondary timeout has to be longer than the primary. Both timeouts are
  * in milliseconds.
  */
 #define PRIMARY_TIMEOUT		500
 #define SECONDARY_TIMEOUT	1000

 #define IPI_TIMEOUT		10000
 #define REAL_MODE_TIMEOUT	10000

 static int time_to_dump;
 /*
  * crash_wake_offline should be set to 1 by platforms that intend to wake
  * up offline cpus prior to jumping to a kdump kernel. Currently powernv
  * sets it to 1, since we want to avoid things from happening when an
  * offline CPU wakes up due to something like an HMI (malfunction error),
  * which propagates to all threads.
  */
 int crash_wake_offline;

 #define CRASH_HANDLER_MAX 3
 /* List of shutdown handles */
 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX];
 static DEFINE_SPINLOCK(crash_handlers_lock);

 static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
 static int crash_shutdown_cpu = -1;

 static int handle_fault(struct pt_regs *regs)
 {
 	if (crash_shutdown_cpu == smp_processor_id())
 		longjmp(crash_shutdown_buf, 1);
 	return 0;
 }

 #ifdef CONFIG_SMP

 static atomic_t cpus_in_crash;
 void crash_ipi_callback(struct pt_regs *regs)
 {
 	static cpumask_t cpus_state_saved = CPU_MASK_NONE;

 	int cpu = smp_processor_id();

 	hard_irq_disable();
 	if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
 		crash_save_cpu(regs, cpu);
 		cpumask_set_cpu(cpu, &cpus_state_saved);
 	}

 	atomic_inc(&cpus_in_crash);
 	smp_mb__after_atomic();

 	/*
 	 * Starting the kdump boot.
 	 * This barrier is needed to make sure that all CPUs are stopped.
 	 */
 	while (!time_to_dump)
 		cpu_relax();

 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(1, 1);

 #ifdef CONFIG_PPC64
 	kexec_smp_wait();
 #else
 	for (;;);	/* FIXME */
 #endif

 	/* NOTREACHED */
 }

 static void crash_kexec_prepare_cpus(int cpu)
 {
 	unsigned int msecs;
 	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 	int tries = 0;
 	int (*old_handler)(struct pt_regs *regs);

 	printk(KERN_EMERG "Sending IPI to other CPUs\n");

 	if (crash_wake_offline)
 		ncpus = num_present_cpus() - 1;

 	crash_send_ipi(crash_ipi_callback);
 	smp_wmb();

 again:
 	/*
 	 * FIXME: Until we will have the way to stop other CPUs reliably,
 	 * the crash CPU will send an IPI and wait for other CPUs to
 	 * respond.
 	 */
 	msecs = IPI_TIMEOUT;
 	while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
 		mdelay(1);

 	/* Would it be better to replace the trap vector here? */

 	if (atomic_read(&cpus_in_crash) >= ncpus) {
 		printk(KERN_EMERG "IPI complete\n");
 		return;
 	}

 	printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
 		ncpus - atomic_read(&cpus_in_crash));

 	/*
 	 * If we have a panic timeout set then we can't wait indefinitely
 	 * for someone to activate system reset. We also give up on the
 	 * second time through if system reset fail to work.
 	 */
 	if ((panic_timeout > 0) || (tries > 0))
 		return;

 	/*
 	 * A system reset will cause all CPUs to take an 0x100 exception.
 	 * The primary CPU returns here via setjmp, and the secondary
 	 * CPUs reexecute the crash_kexec_secondary path.
 	 */
 	old_handler = __debugger;
 	__debugger = handle_fault;
 	crash_shutdown_cpu = smp_processor_id();

 	if (setjmp(crash_shutdown_buf) == 0) {
 		printk(KERN_EMERG "Activate system reset (dumprestart) "
 				  "to stop other cpu(s)\n");

 		/*
 		 * A system reset will force all CPUs to execute the
 		 * crash code again. We need to reset cpus_in_crash so we
 		 * wait for everyone to do this.
 		 */
 		atomic_set(&cpus_in_crash, 0);
 		smp_mb();

 		while (atomic_read(&cpus_in_crash) < ncpus)
 			cpu_relax();
 	}

 	crash_shutdown_cpu = -1;
 	__debugger = old_handler;

 	tries++;
 	goto again;
 }

 /*
  * This function will be called by secondary cpus.
  */
 void crash_kexec_secondary(struct pt_regs *regs)
 {
 	unsigned long flags;
 	int msecs = SECONDARY_TIMEOUT;

 	local_irq_save(flags);

 	/* Wait for the primary crash CPU to signal its progress */
 	while (crashing_cpu < 0) {
 		if (--msecs < 0) {
 			/* No response, kdump image may not have been loaded */
 			local_irq_restore(flags);
 			return;
 		}

 		mdelay(1);
 	}

 	crash_ipi_callback(regs);
 }

 #else	/* ! CONFIG_SMP */

 static void crash_kexec_prepare_cpus(int cpu)
 {
 	/*
 	 * move the secondaries to us so that we can copy
 	 * the new kernel 0-0x100 safely
 	 *
 	 * do this if kexec in setup.c ?
 	 */
 #ifdef CONFIG_PPC64
 	smp_release_cpus();
 #else
 	/* FIXME */
 #endif
 }

 void crash_kexec_secondary(struct pt_regs *regs)
 {
 }
 #endif	/* CONFIG_SMP */

 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
 #if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
 static void __maybe_unused crash_kexec_wait_realmode(int cpu)
 {
 	unsigned int msecs;
 	int i;

 	msecs = REAL_MODE_TIMEOUT;
 	for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
 		if (i == cpu)
 			continue;

 		while (paca_ptrs[i]->kexec_state < KEXEC_STATE_REAL_MODE) {
 			barrier();
 			if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
 				break;
 			msecs--;
 			mdelay(1);
 		}
 	}
 	mb();
 }
 #else
 static inline void crash_kexec_wait_realmode(int cpu) {}
 #endif	/* CONFIG_SMP && CONFIG_PPC64 */

 /*
  * Register a function to be called on shutdown.  Only use this if you
  * can't reset your device in the second kernel.
  */
 int crash_shutdown_register(crash_shutdown_t handler)
 {
 	unsigned int i, rc;

 	spin_lock(&crash_handlers_lock);
 	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 		if (!crash_shutdown_handles[i]) {
 			/* Insert handle at first empty entry */
 			crash_shutdown_handles[i] = handler;
 			rc = 0;
 			break;
 		}

 	if (i == CRASH_HANDLER_MAX) {
 		printk(KERN_ERR "Crash shutdown handles full, "
 		       "not registered.\n");
 		rc = 1;
 	}

 	spin_unlock(&crash_handlers_lock);
 	return rc;
 }
 EXPORT_SYMBOL(crash_shutdown_register);

 int crash_shutdown_unregister(crash_shutdown_t handler)
 {
 	unsigned int i, rc;

 	spin_lock(&crash_handlers_lock);
 	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 		if (crash_shutdown_handles[i] == handler)
 			break;

 	if (i == CRASH_HANDLER_MAX) {
 		printk(KERN_ERR "Crash shutdown handle not found\n");
 		rc = 1;
 	} else {
 		/* Shift handles down */
 		for (; i < (CRASH_HANDLER_MAX - 1); i++)
 			crash_shutdown_handles[i] =
 				crash_shutdown_handles[i+1];
 		/*
 		 * Reset last entry to NULL now that it has been shifted down,
 		 * this will allow new handles to be added here.
 		 */
 		crash_shutdown_handles[i] = NULL;
 		rc = 0;
 	}

 	spin_unlock(&crash_handlers_lock);
 	return rc;
 }
 EXPORT_SYMBOL(crash_shutdown_unregister);

 void default_machine_crash_shutdown(struct pt_regs *regs)
 {
 	unsigned int i;
 	int (*old_handler)(struct pt_regs *regs);

 	/* Avoid hardlocking with irresponsive CPU holding logbuf_lock */
 	printk_nmi_enter();

 	/*
 	 * This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
 	 * The minimum amount of code to allow a kexec'd kernel
 	 * to run successfully needs to happen here.
 	 *
 	 * In practice this means stopping other cpus in
 	 * an SMP system.
 	 * The kernel is broken so disable interrupts.
 	 */
 	hard_irq_disable();

 	/*
 	 * Make a note of crashing cpu. Will be used in machine_kexec
 	 * such that another IPI will not be sent.
 	 */
 	crashing_cpu = smp_processor_id();

 	/*
 	 * If we came in via system reset, wait a while for the secondary
 	 * CPUs to enter.
 	 */
 	if (TRAP(regs) == 0x100)
 		mdelay(PRIMARY_TIMEOUT);

 	crash_kexec_prepare_cpus(crashing_cpu);

 	crash_save_cpu(regs, crashing_cpu);

 	time_to_dump = 1;

 	crash_kexec_wait_realmode(crashing_cpu);

 	machine_kexec_mask_interrupts();

 	/*
 	 * Call registered shutdown routines safely.  Swap out
 	 * __debugger_fault_handler, and replace on exit.
 	 */
 	old_handler = __debugger_fault_handler;
 	__debugger_fault_handler = handle_fault;
 	crash_shutdown_cpu = smp_processor_id();
 	for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) {
 		if (setjmp(crash_shutdown_buf) == 0) {
 			/*
 			 * Insert syncs and delay to ensure
 			 * instructions in the dangerous region don't
 			 * leak away from this protected region.
 			 */
 			asm volatile("sync; isync");
 			/* dangerous region */
 			crash_shutdown_handles[i]();
 			asm volatile("sync; isync");
 		}
 	}
 	crash_shutdown_cpu = -1;
 	__debugger_fault_handler = old_handler;

 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(1, 0);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Architecture specific (PPC64) functions for kexec based crash dumps.
	*
	* Copyright (C) 2005, IBM Corp.
	*
	* Created by: Haren Myneni
	*/

	#include <linux/kernel.h>
	#include <linux/smp.h>
	#include <linux/reboot.h>
	#include <linux/kexec.h>
	#include <linux/export.h>
	#include <linux/crash_dump.h>
	#include <linux/delay.h>
	#include <linux/irq.h>
	#include <linux/types.h>

	#include <asm/processor.h>
	#include <asm/machdep.h>
	#include <asm/kexec.h>
	#include <asm/prom.h>
	#include <asm/smp.h>
	#include <asm/setjmp.h>
	#include <asm/debug.h>

	/*
	* The primary CPU waits a while for all secondary CPUs to enter. This is to
	* avoid sending an IPI if the secondary CPUs are entering
	* crash_kexec_secondary on their own (eg via a system reset).
	*
	* The secondary timeout has to be longer than the primary. Both timeouts are
	* in milliseconds.
	*/
	#define PRIMARY_TIMEOUT 500
	#define SECONDARY_TIMEOUT 1000

	#define IPI_TIMEOUT 10000
	#define REAL_MODE_TIMEOUT 10000

	static int time_to_dump;
	/*
	* crash_wake_offline should be set to 1 by platforms that intend to wake
	* up offline cpus prior to jumping to a kdump kernel. Currently powernv
	* sets it to 1, since we want to avoid things from happening when an
	* offline CPU wakes up due to something like an HMI (malfunction error),
	* which propagates to all threads.
	*/
	int crash_wake_offline;

	#define CRASH_HANDLER_MAX 3
	/* List of shutdown handles */
	static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX];
	static DEFINE_SPINLOCK(crash_handlers_lock);

	static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
	static int crash_shutdown_cpu = -1;

	static int handle_fault(struct pt_regs *regs)
	{
	if (crash_shutdown_cpu == smp_processor_id())
	longjmp(crash_shutdown_buf, 1);
	return 0;
	}

	#ifdef CONFIG_SMP

	static atomic_t cpus_in_crash;
	void crash_ipi_callback(struct pt_regs *regs)
	{
	static cpumask_t cpus_state_saved = CPU_MASK_NONE;

	int cpu = smp_processor_id();

	hard_irq_disable();
	if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
	crash_save_cpu(regs, cpu);
	cpumask_set_cpu(cpu, &cpus_state_saved);
	}

	atomic_inc(&cpus_in_crash);
	smp_mb__after_atomic();

	/*
	* Starting the kdump boot.
	* This barrier is needed to make sure that all CPUs are stopped.
	*/
	while (!time_to_dump)
	cpu_relax();

	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 1);

	#ifdef CONFIG_PPC64
	kexec_smp_wait();
	#else
	for (;;); /* FIXME */
	#endif

	/* NOTREACHED */
	}

	static void crash_kexec_prepare_cpus(int cpu)
	{
	unsigned int msecs;
	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
	int tries = 0;
	int (old_handler)(struct pt_regs regs);

	printk(KERN_EMERG "Sending IPI to other CPUs\n");

	if (crash_wake_offline)
	ncpus = num_present_cpus() - 1;

	crash_send_ipi(crash_ipi_callback);
	smp_wmb();

	again:
	/*
	* FIXME: Until we will have the way to stop other CPUs reliably,
	* the crash CPU will send an IPI and wait for other CPUs to
	* respond.
	*/
	msecs = IPI_TIMEOUT;
	while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
	mdelay(1);

	/* Would it be better to replace the trap vector here? */

	if (atomic_read(&cpus_in_crash) >= ncpus) {
	printk(KERN_EMERG "IPI complete\n");
	return;
	}

	printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
	ncpus - atomic_read(&cpus_in_crash));

	/*
	* If we have a panic timeout set then we can't wait indefinitely
	* for someone to activate system reset. We also give up on the
	* second time through if system reset fail to work.
	*/
	if ((panic_timeout > 0) \|\| (tries > 0))
	return;

	/*
	* A system reset will cause all CPUs to take an 0x100 exception.
	* The primary CPU returns here via setjmp, and the secondary
	* CPUs reexecute the crash_kexec_secondary path.
	*/
	old_handler = __debugger;
	__debugger = handle_fault;
	crash_shutdown_cpu = smp_processor_id();

	if (setjmp(crash_shutdown_buf) == 0) {
	printk(KERN_EMERG "Activate system reset (dumprestart) "
	"to stop other cpu(s)\n");

	/*
	* A system reset will force all CPUs to execute the
	* crash code again. We need to reset cpus_in_crash so we
	* wait for everyone to do this.
	*/
	atomic_set(&cpus_in_crash, 0);
	smp_mb();

	while (atomic_read(&cpus_in_crash) < ncpus)
	cpu_relax();
	}

	crash_shutdown_cpu = -1;
	__debugger = old_handler;

	tries++;
	goto again;
	}

	/*
	* This function will be called by secondary cpus.
	*/
	void crash_kexec_secondary(struct pt_regs *regs)
	{
	unsigned long flags;
	int msecs = SECONDARY_TIMEOUT;

	local_irq_save(flags);

	/* Wait for the primary crash CPU to signal its progress */
	while (crashing_cpu < 0) {
	if (--msecs < 0) {
	/* No response, kdump image may not have been loaded */
	local_irq_restore(flags);
	return;
	}

	mdelay(1);
	}

	crash_ipi_callback(regs);
	}

	#else /* ! CONFIG_SMP */

	static void crash_kexec_prepare_cpus(int cpu)
	{
	/*
	* move the secondaries to us so that we can copy
	* the new kernel 0-0x100 safely
	*
	* do this if kexec in setup.c ?
	*/
	#ifdef CONFIG_PPC64
	smp_release_cpus();
	#else
	/* FIXME */
	#endif
	}

	void crash_kexec_secondary(struct pt_regs *regs)
	{
	}
	#endif /* CONFIG_SMP */

	/* wait for all the CPUs to hit real mode but timeout if they don't come in */
	#if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
	static void __maybe_unused crash_kexec_wait_realmode(int cpu)
	{
	unsigned int msecs;
	int i;

	msecs = REAL_MODE_TIMEOUT;
	for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
	if (i == cpu)
	continue;

	while (paca_ptrs[i]->kexec_state < KEXEC_STATE_REAL_MODE) {
	barrier();
	if (!cpu_possible(i) \|\| !cpu_online(i) \|\| (msecs <= 0))
	break;
	msecs--;
	mdelay(1);
	}
	}
	mb();
	}
	#else
	static inline void crash_kexec_wait_realmode(int cpu) {}
	#endif /* CONFIG_SMP && CONFIG_PPC64 */

	/*
	* Register a function to be called on shutdown. Only use this if you
	* can't reset your device in the second kernel.
	*/
	int crash_shutdown_register(crash_shutdown_t handler)
	{
	unsigned int i, rc;

	spin_lock(&crash_handlers_lock);
	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
	if (!crash_shutdown_handles[i]) {
	/* Insert handle at first empty entry */
	crash_shutdown_handles[i] = handler;
	rc = 0;
	break;
	}

	if (i == CRASH_HANDLER_MAX) {
	printk(KERN_ERR "Crash shutdown handles full, "
	"not registered.\n");
	rc = 1;
	}

	spin_unlock(&crash_handlers_lock);
	return rc;
	}
	EXPORT_SYMBOL(crash_shutdown_register);

	int crash_shutdown_unregister(crash_shutdown_t handler)
	{
	unsigned int i, rc;

	spin_lock(&crash_handlers_lock);
	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
	if (crash_shutdown_handles[i] == handler)
	break;

	if (i == CRASH_HANDLER_MAX) {
	printk(KERN_ERR "Crash shutdown handle not found\n");
	rc = 1;
	} else {
	/* Shift handles down */
	for (; i < (CRASH_HANDLER_MAX - 1); i++)
	crash_shutdown_handles[i] =
	crash_shutdown_handles[i+1];
	/*
	* Reset last entry to NULL now that it has been shifted down,
	* this will allow new handles to be added here.
	*/
	crash_shutdown_handles[i] = NULL;
	rc = 0;
	}

	spin_unlock(&crash_handlers_lock);
	return rc;
	}
	EXPORT_SYMBOL(crash_shutdown_unregister);

	void default_machine_crash_shutdown(struct pt_regs *regs)
	{
	unsigned int i;
	int (old_handler)(struct pt_regs regs);

	/* Avoid hardlocking with irresponsive CPU holding logbuf_lock */
	printk_nmi_enter();

	/*
	* This function is only called after the system
	* has panicked or is otherwise in a critical state.
	* The minimum amount of code to allow a kexec'd kernel
	* to run successfully needs to happen here.
	*
	* In practice this means stopping other cpus in
	* an SMP system.
	* The kernel is broken so disable interrupts.
	*/
	hard_irq_disable();

	/*
	* Make a note of crashing cpu. Will be used in machine_kexec
	* such that another IPI will not be sent.
	*/
	crashing_cpu = smp_processor_id();

	/*
	* If we came in via system reset, wait a while for the secondary
	* CPUs to enter.
	*/
	if (TRAP(regs) == 0x100)
	mdelay(PRIMARY_TIMEOUT);

	crash_kexec_prepare_cpus(crashing_cpu);

	crash_save_cpu(regs, crashing_cpu);

	time_to_dump = 1;

	crash_kexec_wait_realmode(crashing_cpu);

	machine_kexec_mask_interrupts();

	/*
	* Call registered shutdown routines safely. Swap out
	* __debugger_fault_handler, and replace on exit.
	*/
	old_handler = __debugger_fault_handler;
	__debugger_fault_handler = handle_fault;
	crash_shutdown_cpu = smp_processor_id();
	for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) {
	if (setjmp(crash_shutdown_buf) == 0) {
	/*
	* Insert syncs and delay to ensure
	* instructions in the dangerous region don't
	* leak away from this protected region.
	*/
	asm volatile("sync; isync");
	/* dangerous region */
	crash_shutdown_handles[i]();
	asm volatile("sync; isync");
	}
	}
	crash_shutdown_cpu = -1;
	__debugger_fault_handler = old_handler;

	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 0);
	}